During the course of this work, we will characterize in detail the influence of the vestibular system on structures rostral to the level of the vestibular nucleus. The structures principally investigated are thalamus, basal ganglia and cortex. The goals of the project can be divided into three parts. First, we will explore the brainstem pathway involved. This step will be accomplished by recording vestibular evoked responses in cortex while small, progressive lesions are made in selected regions of the brainstem. Secondly, we will investigate the areas of thalamus which respond to vestibular stimulation. Single unit responses and evoked potentials to vestibular nerve stimulation will be described. Finally, the cortical influence on cells of the thalamus will be investigated. Single units which respond to vestibular nerve stimulation will be tested for a response to stimulation of vestibular cortex. BIBLIOGRAPHIC REFERENCE: Abraham, L., Blum, P., Gilman, S.: Multimodal responses in the medial geniculate body of the cat. Neuroscience Abstracts 1:220 (1975).